The purpose of this project is to try and determine answers to questions concerning the relationship between epinephrine, its forming enzyme (phenylethanolamine N-methyltransferase) and blood pressure. We are particularly interested in making a comparative study between these components in the central nervous system (C1 region of medulla ablongata) and in the peripheral system (adrenal gland). The role of epinephrine and PNMT in adrenal gland has been studied quite extensively while such studies in the brain are lacking. Recently, however, there has been increasing interest in the adrenergic system of brain. Current studies from our laboratory as well as the literature have shown that: 1. Brain PNMT levels are significantly elevated in young SHR as well as in rats with experimentally induced hypertension when compared to their respective controls. This increase in PNMT levels is not observed in adrenal glands. 2. Epinephrine content in various regions of the brain parallels the PNMT concentrations. 3. PNMT from the C1 region of the medulla oblongata appears to be similar to the adrenal enzyme. In fact, enzymes in both regions seem to be regulated in part by the adreno-pituitary axis.